Method and apparatus for producing and stretching artificial yarn



April 20, 1948. I H. w. SWANK I 2,440,226

METHOD AND APPARATUS FOR PRODUCING AND STRETCHING ARTIFICIAL YARN FiledMay 31, 1946 4 Sheets-Sheet 1 INVEN TOR A I TURNE v.

April 1948- H. w. SWANK 7 2,440,226

METHOD AND APPARATUS FOR PRODUCING AND STRETCHING ARTIFICIAL YARN filedMay 31, 1946 4 Sheets- Sheet 2 INVENTOR B I fiawapolllswnm A TTOENEY.

April 20, 1948- v H. w. S'WANK 2,440,226

METHOD AND APPARATUS FOR PRODUCING AND STRETCH ING ARTIFICIAL YARN FiledMay 31, 1946 4 Sheets-Sheet 3 INVENTOR B HOWAkDWSH/ANA nrromvtx April20, 1948. H. W.'SWANK 2,440,226

METHOD AND APPARATUS FOR PRODUCING AND STRETCHING ARTIFICIAL YARN FiledMay 31, 1946 4 Sheets-Sheet 4 'INVENTOR Hon 4,00 WSW/91w" A TTORNEY Patented Apr. 20, 1948 METHOD AND mm'rus ron raonvcmo am) s'rasrcnmc,aarmcmr. man

Howard w. Swank, Richmond, vs. assignor to E. I. du Pont de Nemours &Company, Wiln, Del, a corporation of Delaware Application May :1, 1m,Serial No, 873,446

' 21 Claims. (01. 18-8) 1 This invention is a continuation-in-part ofcopending application Serial No. 499,162. filed August 19, 1943, andrelates to the manufacture of regenerated cellulose yarn from viscose.More particularly, this invention relates to a method and apparatus fordrawing freshly spun, yarn around a feed wheel for use in the productionof viscose rayon and particularly for use in the hot dip method toproduce high tenacity regenerated cellulose yarn of substantiallyuniform physical characteristics.

United-States Patents No. 1,901,007 of March 14, 1935, and No. 1,996,989of April 9, 1935, disclose procedures for producing viscose rayon ofimproved tenacity by passing the coagulated partially regeneratedfilaments through a hot aqueous bath heated to 70 C. to 100 C. and,while the filaments are in contact with such hot aqueous bath,subjecting them to substantial tension and/or stretching. In each of theprocedures disclosed in the aforementioned patents, the amount ofswelling or plasticizing of the yarn by the hot water treatment was notreadily controllable and the application of stretch over a substantiallength of the yarn did not give consistent reproducible results so thata product of uniform characteristics could be obtained.

United States Patent No. 2,248,862 of July 8,

1941, discloses a hot bath stretching arrangement wherein the first feedwheel is partially immersed in the hot bath and whereby the hot bath isapplied only at the bottom of the feed wheel. The application 01 the hotbath to the first feed wheel only at the bottom thereof limits thetakeoif point of the yarn to the side of the feed wheel and at a pointnot greater than 60 from the point where the feed wheel contacts the hotbath if the thread is to be at the maximum temperature (and this isnecessary for optimum re-- sults) at the time of stretching. If thethread were taken off at some other point greater than 60 from the pointof application of the hot bath, such as from the top of the firstfeedwheel in its passage to the second feed wheel, the temperature ofthe thread at the time of stretching would be less than the temperatureof the bath due to cooling by evaporation from the feed wheel.

Additionally, such arrangement is objectionable in that it prevents-theimposition of the maximum possible spinning tension, such as of theorder of 1 gram per denier, between the two positively driven rollers.It is well recognized that the tenacity of yarn produced is dependent toa very large extent on the amount of tension imposed on the partiallyregenerated yarn, and

formed yarn is apparently due to the fact that stationary yamdirectionalguides are used and the frictional resistance to the travel of the yarnmakes it necessary to spin at lower tensions than would be possible ifthe yarn came in contact with'substantially no frictional resistance.Further, the application of a hot bath to the yarn passing aroundtheroller, as disclosed in said Patent No. 2,248,862, is not suited tothe optimum control of stretching as will be more fully explainedhereinafter.

slippage of the freshly formed yarn on the feed wheels when yarn wasbeing spun by the bucket spinning process was a. major problem someyears ago. The use of double wraps around the feed wheel andespeciallythe use of a freely rotatable snubber guide roller, such asshown in United States Patent No. 1,977,611, was decidedly helpful inthe development of yarn of more uniform properties. However, in thespinning of large denier yarns, such as 1100 denier,

under high tension, and especially when the yarn is treated with a hotaqueous bath and stretched a. substantial amount, a small number of thefilaments are commonly broken. Thehot bath does not act instantaneouslyon all the filaments comprising the bundle and, as soon as most of thefilaments become plasticized, they stretch, releasing a large part oftheir load to the less plasticized filaments which bear or try to bearan unproportionally large load, and finally break.

Thesebroken filaments most frequently wrap around the snubber guideroller, continue tobuild up, and often cause other filaments to break,until the entire bundle breaks or until the wrap becomes so large as toprevent normal operation of the roller.

In addition. the advent of much higher spinning tensions (of the orderof 1 gram per denier) made necessary in order to maintain a high degreeof uniformity a plurality of complete wraps around the feed wheel andtwo or more wraps around the snubber roller guide. While slippage of theyarn on the stretching wheel was thus avoided, increased roller wrapswere a barrier against any practical application. It is, of course,apparent that in spinning at tensions well below the yarn breakingtension many of these difliculties never arise. Nevertheless. whenspinning at speeds 25% to 50% higher than commonly used and at maximumtensions on the filament bundle within 80% to 95% of the breakingtension, what would normally be considered extremely minorirregularities become of extreme importance and the procurement ofoptimum benefits from this extremely high tension spinning are vitallydependent on every minute refinement.

It is an object of this invention to provide an improved process fordrawing freshly spun yarn around a feed wheel.

Another object is to present the yarn to the feed wheel during itspassage therearound in a substantially uniform bundled form free offloating or wandering filaments.

Another object is to presentithe yarn to be. stretched in a uniformlybundled form substantially free of floating or wandering filaments.

Another object of this invention is to stretch the freshly spun viscoserayon yarn impregnated with a hot aqueous liquid between two feed wheelsand substantially reduce or indeed inhibit the formation of filamentwraps on the snubber guide roller.

A further object of this invention is to provide an apparatus forcarrying out the aforementioned process.

A still further object of the invention is to provide a novel means forbundling the freshly formed yarn to. prevent filament wraps on thesnubber guide :oller.

mentioned. The peripheral speeds 'of the feed wheels are such as toimpose in the yarn a total tension of the order of 1 gram per denier. Aswill become apparent hereinafter, the stretch is confined within a shortdistance in the path of travel of the yarn (as it comes onto the firstfeed wheel and as it leaves said feed wheel) and at a time when the yarnis uniformly impregnated with the hot aqueous bath.

In that embodiment-of this invention which is directed to improvementsin the process involving hot aqueous bath stretching the bath may bewater, acidulated water, or a viscose regenerating bath of the same ordifferent composition as that into which the viscose is initially spun.It has been found that optimum results are obtained by applying to theyarn to be stretched a bath heated to a temperature of about 90 C. to 95C. so that stretching will take Place in yarn that is not below 85 C. atthe region and time of stretching, although excellent results can oftenbe obtained by impregnating the yarn to be stretched at much lowertemperatures, such as at 75 C. or thereabouts.

The details of the invention will become more apparent by reference tothe accompanying drawings when taken in connection with the fol- Ilowing detailed description.

A still further object is to provide a novel snub- I ber guide roller.

Other objects will be apparent from the description hereinafter setforth.

The objects of the invention are generally accomplished by passingfreshly spun viscose rayon yarn one or more times over and around a feedwheel and, between each successive pass of the yarn over the feed wheel,passing the yarn under a freely rotatable snubber roller that preventsthe yarn from tracking on itself and imparts a twist to the yarnimmediately prior to its contact with the snubber roller. The twistgreatly reduces the formation of filament wraps on the snubber rollerand is substantially removed, leave ing the filaments bundled togetherand the yarn substantially free from loose and wandering filamentsbefore the yarn again contacts the feed wheel. The yarn leaving the feedwheel can be collected in an appropriate collection device. In anotherembodiment of the invention, freshly spun viscose rayon is stretchedbetween two positively driven feed wheels, the yarn passing one or moretimes around the first feed wheel and a plurality of times around thesecond feed wheel. While the yarn is on the first feed wheel, it isuniformly impregnated with a hot aqueous liquid. In the passage of theyarn over and around the first feed wheel, the yarn is passed under afreely rotatable displacement snubber roller to prevent the yarn fromtracking onitself and to impart twist thereto. The twist is imparted tothe yarn at a point immediately prior to its contact with the snubberroller, and the formation of filament wraps on the snubber roller isgreatly reduced. The twist is substantially removed, leaving thefilaments bundled together and the yarn substantially freeof loose orwandering filaments, before the yarn again contacts the first feedwheel. The yarn is then passed over and around the second feed wheel,which is also provided with a snubber roller guide. of the typepreviously In the drawings,

Figure 1 is a perspective view, partly in section, showing an apparatussuitable for carrying out the invention;

Figure 2 is a front elevation of the first stretching wheel and thesnubber roller cooperating therewith, and also showing the zone of hotbath application;

Figure 3 is a side elevation of the set-up shown in Figure 2;

Figure 4 is an enlarged front elevation, partly in section, of the meansfor applying the hot aqueous bath;

Figure 5 is a top plan view, broken away for clarity, showing thearrangement of the snubber roller with respect to the feed wheel;

Figure 6 is a modified form of snubber roller suitable for use when twopasses of the yarn are made about the snubber roller;

Figure 7 is a section of another modified form of snubber rollersuitable for use when two passes reference numerals designate likeparts, the reference numeral ill designates a multi-hole spinneretthrough which the viscose solution, supplied thereto through a conductl2, is. extruded into a spinning bath l4 contained in a. trough I. Thefilaments I8 extruded within the bath through the spinneret iii arepassed around guides 20, 22, 24, 26 and 28 positioned beneath the levelof the bath. The guide 28 is designed to impose a tension on the yarnand may be of the type shown in United States Patent No.'2,083,251. Theyarn 30 is withdrawn from the bath H by a positively driven feed wheel32 and passed once around said feed wheel 32. In its passage over,,

pluralityv of times around a second positively driven feed wheel 33. Theyarn 33, in its passage around the feed wheel 33, also passes under afreely rotatable snubber roller 33. The feed wheels 32 and 33 aremounted on shafts "and -42, which are driven by means (not shown) atsuch rates that the peripheral speed of the wheel 33 is greater than theperipheral speed of the wheel 32 whereby the yarn between said wheels isstretched, After leaving the feed wheel 33, the

the let be determined to control the amount of preliminary stretch togive the best results. By this process. the yarn that is stretched inthe primary bath is then given a preliminary small amount of stretchingbefore becoming positively engaged on the feed wheel and is then broughtto a temperature of about 90' C. just prior to its flnal yarn iscollected in a rotating bucket 44 into which it is guided by areciprocating funnel 43.

While the yarn 30 is on the first feed wheel 32, it is impregnated witha jet of hot aqueous bath 50.

The feed wheel 32 is provided at the rear thereof with an upwardlyinclined (slinger ring) flange 54, from which the hot bath liquidapplied to the feed wheel is discharged into a collecting shroud 58 fromwhich it is removed by a conduit 58. In order that the bath bedischarged from the feed wheel 32 only at the flange 34, the Jet of hotliquid 30 is applied to the upper portion of the feed wheel 32 withintherange of 120. as shown in Figure 2, and the thread-contacting portion59 of the feed wheel is constructed with a slighttaper, as indicated bythe reference character A in Figure 3, to insure that centrifugal forcewill drive the "liquid from the thread-contacting portion 53 of the feedwheel 32 to the point of the flange 34 before discharging it from thewheel. While this taper A may be no more than 1", preferably it isgreater than 3", but in no case more than 6 or 8.

The region of application of the jet ill will vary with the contour ofthe feed wheel 32, the peripheral speed and radius thereof. when theyarn '30 leaves the wheel 32 at the top, as indicated in Figure 2 by thereference character T, the Jet 50 is located preferably at an angle of10 or anywhere within the 75? angle, designated as C in Figure 2. Whenthe yarn leaves the wheel 32 from the side, referred to as "alternateroute of thread" and designated by the reference character S, the Jet 30is directed onto the wheel 32, preferably at the top center or anywherewithin the 45 angle marked D. In these embodiments, the Jet of hot bathliquor II is applied to the yarn within a. zone of an angle of about 90from the point the yarn leaves the wheel, and it is preferably also sodirected as to have a component of its velocity in the .direction ofrotation of the wheel 32.

Part of the stretching of the yarn 30 takes place over the surface 39 ofthe feed wheel 32 just before the yarn loses contact with the wheel.resulting in slippage of the yarn on the wheel. It is, therefore,important that the yarn be in the most plastic condition possible tokeep this slippage at a minimum, and to provide plenty of lubrication bymeans of a liquid so that this slippage will not damage the yarn. Someslippage also occurs in the region where the yarn 30 first contacts thewheel 32. since the surface 59 of the wheel is wet with the hot treatingliquor. The tension device 23 located in the spinning bath i4 serves asa retarding force on the yarn, which stretches the partially heated yarnon the feed wheel before sufficient contact of the surface is presentbetween the yam and the feed wheel to prevent slippage. It is,therefore. very important that the point of application of the hot bathjet 50 be uniform on the wheel 32 from position to position and that thedesired point of application of wheel 32.

stretching between the feed wheels. The optimum location of the Jet willvary somewhat, as previously indicated. depending on the peripheralspeed and radius of the feed wheel.

Several factors are considered in the construction of the Jet and theexact angle of impingement of the bath on the wheel. The temperature ofthe hot aqueous bath liquid drops from the time it first contacts theyarn until it is removed from the wheel. The absolute temperature dropacross the wheel will be determined by the absolute magnitude of flow ofthe hot bath. Since it is desired to keep the temperature drop at aminimum, fairly large flows of hot bath are used.

In the form shown in the drawings, the Jet 30 is obtained through theuse of a pipe 82, which is provided with an oriflce 34 at a suflicientdistance from the mouth of the pipe to permitthe Jet 30 to be. suppliedin a smooth large flow and to prevent splashing of the Jet when itimpinges on the The pipe 32 is secured to the shroud. as shown inFigures 2 and 3, and thehot bath liquid is supplied at a constantpressure to the top thereof from a source (not shown).

As previously mentioned, the jet is directed so as to have somecomponent of its velocity in the direction of rotation of the wheel. Theyarn lies on the feed wheel in the form of a ribbon, due to theextremely high tension imposed on the yarn and its normal tendency tohug the wheel, and the direction of the jet upon this ribbon of yarnwith positive force achieves mort rapid penetration of heating liquorinto the yarn.

It is desirable to eliminate all sharp corners or edges from the feedwheel 32, thereby eliminating points and edges from which the bath maybe discharged from the feed wheel rather than be pumped to the slingerring flange 34 where it is discharged into the shroud 33. The propercontour of the feed wheel 32 is also partially determined by the anglbetween the plane of rotation of the feed wheel 32 and the horizontal.If the 'thread-contacting. surface 88 slopes too steeply from the flangeN to the front of the feed wheel 32, gravity partially overcomescentrifugal force and the treating liquor is discharged from the frontof the feed wheel. The flow of hot bath along the upper surface of thewheel is aided by tilting the plane of rotation of the wheel from thevertical by an amount approximately equal to the degree of taper of thefeed wheel. a

In the set-up shown in Figures 1, 2 and 3, the yarn 30 is given one passunder the snubber roller 34. In such a set-up. the snubber roller 34 maybe like that described in United States Patent No. 1,977,611. Asdescribed in said patent, the snubber roller 34 has a frusto-conicalthread-contactingportion 33 and an upwardly inclined flange 83 at therear thereof. The snubber roller 34 is freely rotatable on a stud i0,and the flange i3 is positioned within a shroud 12. ,A pipe 14 conductsany liquor, which passes from the snubber roller 34 to the shroud 12, tothe conduit 33.

In order to satisfy the requirements of this in vention. the snubberroller 34 must be positioned passing through the axis of the feed wheelby a small angle of about 6' or 8'.

By locating the snubber guide 30 in thisfmannor, the yarn 30 coming downfrom the feed wheel 02 first contacts the flange of the snubber 00 and,due to the askew position thereof, rolls down the flange onto the (lesstapered) frustc-conical body 00. Because the yarn rolls on itself incoming onto the snubber roller 04. it develops temporarily a certainamount of twist. The twist actually takes place between the point atwhich the yarn leaves the feed wheel I! and the contact point with thesnubber guide roller 04, so that the yarn contacting the snubber roller34 is well bundled and broken filaments are not picked up and wrappedaround the snubber roller 34 but are carried along as part of thecontinuous filament bundle. when the yarn leavesthe snubber roller 04and travels to the feed wheel 32, thetwist is removed. However, due tothe brief existence of the twist. the many filaments comprising the yarnare more closely bundled together than they would be otherwise, and theyarn is prevented from being spread out as a wide ribbon on the snubberroller 00. As previously stated, due to the high tension imparted inthe'thread, it is appreciably flattened as a ribbon on the wheel 32, butthe filaments are still all sumciently united that, when substantialstretching of the yarn takes place, each filament more uniformly assumesits share of the load.

The arrangement shown in Figures 2, 3 and 5 illustrates one wrap aroundthe snubber roller, which is entirely satisfactory when the tensiondifferential between the oncoming yarn and the yarn leaving is not toogreat. when this differential is large, then the yarn should be giventwo or more passes around the feed wheel and snubber roller.

If two passes of the yarn are to be made about the snubber guide roller,snubber guide rollers of the type shown in Figures 6 and 7 may be used,and the twist will be imparted to the yarn in its two successive passestherearound.

Referring now toFlgure 6, the reference numeral 00 designates aone-piece snubber roller which can be used when the yarn is given twopasses about it. This snubber roller 00 is provided with twothread-contacting portions 02 and 04 having the same diameter and twoflanges 00. and 00 of the same angularity. This snubber roller 80 ispositioned in the same askew position as the snubber roller 00, andthe'yarn 00 is directed first onto the flange 00, from which it isrolled onto the thread-contacting surface 02 to ,impart the temporarytwist. In its second pass,

the yarn 30 is fed onto-the flange 00 and is rolled onto thethread-contacting surface ,84 whereby the temporary twist is imparted tothe thread. When snubber roller 00 is used, any filament wraps whichoccur between the flanges l0 and 00 can be removed only with somedifficulty.

The modified snubber roller designed to take two passes of the yarntherearound and to satisthereto, shown in Figure '7, comprises twoelements 00 and 02 which are independently and freely rotatable on astub shaft 0|, one end of which is fixedly mounted in a shroud 00. Therotatable elements 00 and 02 are held on the shaft by means of apress-fit washer 00. The element 00 has a substantially cylindrical bodyI02 and an inclined flange I04 at' the rear thereoi. The element 02 alsohas a substantially cylindrical body I00 and an inclined flange I00which terminates in a small cylindrical flange III. The rotatableelement 02 is smaller than the element 00 and it is so mounted that thesubstantially cylindrical body I02 of the element 00 overlaps and isspaced from the flange IIO of the element 02. As is shown in Figure 'I,the

, element 02 is provided on the rear end thereof with a boss III whichis positioned in a recess Ill and on the front face of the element 00.While the-liquid discharged from the element 02 generally flows over therounded shoulder of the element 00, due to the action of centrifugalforce a certain amount may .be discharged into the recess I It, in whichcase it is conducted by means of ducts IIO to a passage I I0, from whichit is removed by the conduits I20. The liquid from the element 00 isdischarged in the passage III. In operation, this snubber roller ispositioned in the same askew manner beneath the feed wheel 02 as thesnubber roller 04, and as diagrammatically shown in Figure 8.

In operation, the yarn 00, as it comes from the feed wheel, is led ontothe flange I04, from which it rolls onto the thread-contactingcylindrical surface I02 and whereby the temporary twist is imparted tothe yarn. In its second passage, the yarn 00 is led onto the flange I00,from which it rolls onto the thread-contacting cylindrical surface I00whereby the temporary twist is imparted. By having both elements 00 and02 independently rotatable, each of them seeks its own speed of rotationwhen driven by the yarn passing therearound. In this way, any chance offrictional rubbing of the yarn on the surface is avoided because onlyone path of the yarn is in contact with each independent rotatableelement of the guide. The slope of the flanges I04 and I00 is preferablyabout 40 to 50 with respect to the axis of rotation.

If more than two passes of yarn around the feed wheel are desired, thesnubber roller hereinbefore described may be substituted by snubberrollers having three or more independently rotatable elements of. thetype shown in Figure 7, or, when a single roller is used, three or moreflanges and thread-contacting surfaces of the type shown in Figure 6.

The snubber roller 30 may be of any of the types herein described,depending of course on the number of passes the yarn makes therearound.Because. of the high tension on the oncoming side and the relatively lowtension on the yarn leaving the second feed wheel 00, it is preferredand more generally needed to use snubber rollers of the type shown inFigures 6 and '7 wherein a double pass of the yarn about the snubberroller is obtained.

The feed wheelsand the snubber guides herein described are constructedof such surface material that sulfur 'and sludge from .the spinning bathwill not adhere in the yarn path, forming ridges from which the hotliquid will be discharged without flowing to the flange. A glass surfacehas given satisfactory results.

Instead of collecting the yarn in, a bucket, it can be'collected on abobbin.

To fiuther illustrate this invention, the following specific example,wherein proportions are by weight, is given:

Example A viscose solution containing 7% cellulose, 63%

NaOH ripened to.a sodium chloride salt index stretch applies additionaltension, so that be-;

tween the two feed wheels the tension is equal to 1060 grams. The yarnis collected in a centrifugal spinning bucket under an average tensionof about 15 grams (measured between the second feed wheel and the bucketfunnel), and in view of this great tension differential three passes ofyarn are made over the second feed wheel, necessitating a double pass ofyarn under the snubber roller guide, although but a single pass isneeded under the snubber roller guide associated with the first of thestretching feed wheels since the tension differential here is relativelysmall.

During .5 hours of spinning, using the double roller guide shown inFigure 7 under the second feed wheel and so positioned that a temporarytwist was produced in the yarn with each pass thereto, not a-single wrapwas formed and the yarn produced was oi uniform high quality with thedesired high tenacity. However, when this. double roller snubber guidewas replaced with a one-piece cylindrical roller under which the yarnpassed without the benefit of temporary twist being applied thereto,eight wraps were formed during a hour period. of which two wraps builtup so large by entanglement of other filaments that the yarn was broken.

This invention enables the production of yarn of substantially uniformphysical properties having a desirably high elongationas well as hightenacity, good knot strength, and excellent fatigue value. Such yarn iseminently suited for the manufacture of cord for use in thereinforcement of rubber structures, such as rubber tires, steam hose'andthe like, and is also useful in many other fields where high strengthand reasonable good elongation are desired. This invention permits theproduction of yarns of higher average dry tenacities than have beenpossible heretofore by the hot bath spinning method and greatly reducesspinning difficulties.

The invention is not restricted to stretching, between two spacedpositively driven feed wheels, viscose yarn impregnated with a hotaqueous liquid. The invention, and particularly the set up of feed wheel32 and snubber roller 34 hereinbefore described, can be employed in anyapparatus or process wherein a yarn is passed one or more times around afeed wheel to avoid sli viously described, whereby,

agulates and regenerates the viscose and, if desired, the yarn canbestretched during its passage therethrough as hereinbefore described,and the feed wheel 32 draws the freshly produced yarn therefrom.slippage of the yarn on the eed wheel I2 is avoided by means of thesnubber roller 34, under which the yarn passes between each successivepass about the feed wheel 32. The snubber roller 84 is of theconstruction, and mounted relative to the feed wheel 32 as prein thepassage of the yarn from the feed wheelto the snubber roller, the yarnwill be twisted and the twist will leave the yarn after the yarn leavesthe snubber roller in its travel back to the feed wheel. The yarn, uponleaving the feed wheel, funnel 48 into the bucket II where is itcollected in the form of a cake.

In the embodiment described immediately pre- 1 ceding, the snubberroller can be of arv of the types previously described, depending 'onthe number of passes the yarn makes therearound, such roller beingpositioned, as hereinbefore described, so that the twist will beimparted to the yarn in each of its successive passes thereto.

The method of applying the jet of hot aqueous liquid on the first feedwheel per se forms no part of this invention (except in the combinationdisclosed herein) and forms the subject-matter of application Serial No.499,162. v

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited thereto except as set forth in the appended claims.

I claim:

1; In the process of drawing freshly spun yarn around afeed wheel andavoiding slippage of the yarn thereon, the steps which comprise passingthe yarn from said feed wheel under a freely rotatable snubber roller toprevent the yarn from tracking on itself, and imparting a twist to saidyarn in its passage to said snubber roller.

2. In the process of drawing freshly spun yarn around a feed wheel andavoiding slippage of the yarn thereon, the steps which comprise passingthe yarn from said feed wheel under a freely rotatable snubber roller toprevent the yarn from tracking on itself, imparting a twist to said yarnin its passage to said snubber roller, and permitting the twist to leaveafter the yarn passes from said snubber roller in its travel back tosaid feed wheel.

3. In the process of drawing freshly spun yarn around a feed wheel andavoiding slippage of the yarn thereon, the steps which comprise passingthe yarn from said feed wheel under a freely rotatable snubber roller toprevent the yarn from tracking on itself, and imparting a twist to saidyarn betweenthe point it leaves said feed wheel page thereon and asnubber roller is employed to prevent the yarn from tracking on itself.Thus, for example, the feed wheel 32 and the freely rotatable snubberroller 34 arranged as hereinbefore described can be positioned betweenthe and the point it contacts said snubber roller.

' 4. In the process of drawing freshly spun yarn around a feed wheel andavoiding slippage of the yarn thereon; the steps which comprise passingthe yarn from said feed wheel under a freely rotatable snubber roller toprevent the yarn from tracking on itself, imparting a twist to said yarnbetween the point it leaves said feed wheel and the point it contactssaid snubber roller, and per-, mitting the twist to leave after the yarnpasses from said snubber roller in its travel back to said feed wheel.

5. In the process of drawing freshly spun yarn around, a feed. wheel andavoiding slippage of the is directed by the yarn thereon,

the yarn a plurality -a,44o,saa 1 I 12 roller. permitting the twist toleave the yarn after the yarn passes from said snubber roller in itstravel back to said feed wheel, and conducting...

the yarn after it finally passes from said feed feed wheel to saidsnubber spaced positively driven feed wheels viscose yarn impregnatedwith a hot aqueous liquid, the steps which comprise passing theyarn fromone of said feed wheels under a freely rotatable snubber roller toprevent the yarn from tracking on itself, and imparting a twist to saidyarn in its passage to said snubber roller.

7. In the process of stretching between two spaced positively drivenfeed wheels viscose yarn impregnated with a hot aqueous liquid, thesteps which comprise passing the yarn from at least one of said feedwheels under a freely rotatable snubber roller on itself, imparting atwist to said yarn in its passage to said snubber roller, and permittingthe twist to leave after the yarn passes from said snubber roller in itstravel back to said feed wheel.

8-. In the process of stretching between two spaced positively drivenfeed wheels viscose yarn impregnated with a hot aqueous liquid, thesteps which comprise passing the yarn from at least one of said feedwheels under a freely rotatable snubber roller to prevent the yarn fromtracking on itself, and imparting a twist to said yarn between the pointit leaves said feed wheel and the point it contacts said snubber roller.

9. In the process of stretching between two spaced positively drivenfeed wheels viscose yam impregnated with a hot aqueous liquid, the stepswhich comprise passing the yarn from at least one of said feed wheelsunder a freely rotatable snubber roller to prevent the yarn fromtracking on itself, imparting a twist to said yarn between the point itleaves said feed wheel and the point it contacts said snubber roller,and permitting the twist to leave after the yarn leaves said snubberroller in its travel back to said feed wheel.

10. In the process of stretching between two positively driven feedwheels yam impregnated with a hot liquid, the steps which comprisepassing the yarn a plurality of times about one of said feed wheels,passing the yarn a plurality of times about a freely rotatable snubberroller in its successive passages about said feed wheel, im-. parting atwist to said yarn in each successive passage from said feed wheel tosaid snubber roller, and permitting the twist to leave after the yarnleaves said snubber roller in its travel back to said feed wheel.

11. A method of producing high tenacity viscose rayon yarn whichcomprises extruding a viscose solution into a spinning bath, withdrawingthe yarn from said bath, passing the yarn around a positively drivenfeed wheel, applying a jet of hot aqueous liquid to the yarn on saidfeed wheel and while it is within a. zone of 90 from the point it leavessaid wheel, the temperature of said aqueous liquid'being such as to heatthe yarn to a temperature of at least 75 0., passing the yarn around afreely rotatable snubber roller in its passage around said feed wheel toprevent said yarn from tracking on itself, imparting a to prevent theyarn from tracking wheel to a second feed wheel having a peripheralspeed higher than that of the first feed wheel,

12. A method of producing high tenacity viscose rayon yarn whichcomprises extruding a viscose solution into a spinning bath, withdrawinthe yarn from said bath, passing the yarn around a positively drivenfeed wheel, applying a jet of aqueous liquid heated to a temperature offrom- 90' C, to 95 C. to the yarn on said feed wheel and while it iswithin a zone of 90 from the point it leaves said wheel, passing theyarn around'a freely rotatable snubber roller in its passage around saidfeed wheel to prevent said yarn from tracking on itself, imparting atwist to said yarn in its passage to said snubber roller, permitting thetwist to leave the yarn after the yarn passes from said snubber rollerin its travel back to said feed wheel, and conducting the yarn after itfinally passes from said feed wheel to a second feed wheel having aPeripheral speed higher than that of the first feed wheel.

13. A method of producing high tenacity viscose rayon yarn whichcomprises extruding a viscose solution into a spinning bath, withdrawingthe yarn from said bath, passing the yarn around a positively driven'feed wheel. applying a jet of hot aqueous liquid to the yarn on saidfeed wheel and while it is within a zone of 90 from the point it leavessaid wheel, the temperature of said aqueous liquid being such as to heatthe yarn to a temperature of at least 0., passing the yarn around afreely rotatable snubber roller in its passage around said feed wheel toprevent said yarn from tracking on itself, imparting a twist to saidyarn between the point it leaves said feed wheel and the point it firstcontacts said snubber roller. permitting the twist to leave the yarnafter the yarn passes from said snubber roller in its travel back tosaid feed wheel, and conducting the yarn after it finally passes fromsaid feed wheel to a second feed wheel having a peripheral speed higherthan that of the first feed wheel.

14. A method of producing high tenacity viscose rayon yarn whichcomprises extruding a viscose solution into a spinning bath. withdrawingthe yarn from said bath, passing the yarn around a positively drivenfeed wheel, applying a jet of hot aqueous liquid to the yarn on saidfeed wheel, and .while it is within a zone of from the point it leavessaid wheel, the temperature of said aqueous liquid being such as to heatthe yarn to a temperature of at least 75 (3., passing the yarn around afreely rotatable snubber roller in its passage around said feed wheel toprevent said yarn from tracking on itself, imparting a twist to saidyarn in its passage to said snubber roller, permitting the twist toleave the yarn after the yarn passes from said snubber roller in itstravel back to said feed wheel, conducting the yarn after it finallypasses from said feed wheel to a second feed wheel having a peripheralspeed higher than that of the first feed wheel, passing the yarn aplurality of times about said second feed wheel, passing the yarn aplurality of times about a freely rotatable snubber I twist to said yarnin its passage to said snubber 75 roller, and permitting the twist toleave after the yarn leaves the snubber roller in itstravel back to saidsecond feed wheel.

15. A method as set forth in claim 14, wherein the temperatures of thehot aqueous bath is from 90 C. to 95 C. Y

16. In combination a feed wheel over and about which yarn is passed anda freely rotatable snubber roller to displace the yarn passing aboutsaid feed wheel, said snubber roller having a plurality of inclinedflanges and a body portion in advance of each flange, the front edge ofthe body portion last engaged by the yarn being free, said snubberroller being mounted askew to said feed wheel whereby in the successivepassages of the yarn from said feed wheel to said snubber roller it willpass successively onto the respective flanges and roll therefrom to thebody portion forwardly thereof to impart a twist in said yarn.

17. In combination a feed wheel over and about which yarn is passed anda freely rotatable snubber roller to displace the yarn passing aboutsaid feed wheel, said snubber roller having a plurality of flangesinclined at the same angularity with' respect to the axis of rotation ofsaid snubber roller and a body portion in, advance ofreach flange, thefront edge of the body portion'last engaged by the yarn being free, saidsnubber roller being mounted askew to said feed wheel whereby in thesuccessive passages of the yarn from said feed wheel to said snubberroller it will pass onto the respective flange and roll therefrom to thebody portion forwardly thereof to impart a twist in said yarn.

18. The combination as set forth in claim 16 wherein the snubber rolleris formed of one piece.

19. The combination as set forth in claim 17 wherein the snubber rolleris formed of one piece and has two flanges and two body portions.

20. The combination as set forth in claim 16 wherein the snubber rolleris formed of one piece and the body portions in advance of each flangebeing of substantially the same diameter.

21. The combination as set forth in claim 17 wherein the snubber rolleris formed of one piece and has two flanges and two body portions, saidbody portions being of substantially the same diameter.

HOWARD W. SWANK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

